Fenris Games have released a multi-part 28mm rowing boat kit.
From their announcement:
We’ve started 2010 with the release of a new mini kit suited to 28mm miniatures. This is a four part urethane resin and laser-cut ply kit building into a typical wooden hulled rowing boat complete with separate gunwales and oars. Designed to show a low waterline model, this is easily remodelled to suit a range of periods and styles.